Disaster and Emergency Management Presidency

Presidency, Turkey

Disaster and Emergency Management Presidency

Presidency, Turkey
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Gokten E.,Ankara University | Demirtas R.,Disaster and Emergency Management Presidency | Ozaksoy V.,Akdeniz University | Herece E.,General Directorate of Minereal Research | And 2 more authors.
Turkish Journal of Earth Sciences | Year: 2011

The Bolu Basin in northwestern Turkey, situated in the western part of the North Anatolian Fault Zone (NAFZ), displays the neotectonic features of a pull apart basin. The long axis of the basin extends east-west, parallel to the fault zone and Bolu city, situated in the central part of this basin, was extensively damaged during the 17 August 1999 M= 7.4 and 12 November 1999 M= 7.2 earthquakes. The master strand of the North Anatolian Fault Zone cuts through the basin close to its southern edge and movement on this strand has caused tilting of the basin floor towards the south because of a small dip slip component. Almacik Mountain, to the west of the Bolu Basin, is interpreted as a plate flake and appears to play a role in the bifurcation of the North Anatolian Fault Zone around the Düzce Basin, to the west of Bolu. Thus the surface fracture associated with the right-lateral strike-slip Gölyaka-Kaynaşli{dotless} segment of the NAFZ (which caused the 12 November 1999 M= 7.2 earthquake in this region), can be traced along the northern flank of Almacik Mountain and may extend into the middle of the Bolu Basin from the west. The northern boundary of this basin is controlled mainly by an E-W-striking oblique-slip normal fault with a right-lateral strike-slip component but a major NE-SW-trending younger fracture (Kocasu Fault) has also influenced the kinematic behaviour of this sector of the NAFZ and the adjacent basin. It is concluded that the Bolu Basin opened as a pull-apart basin since the Early Pleistocene between the northern boundary faults and southern master strand, and within the complex stress-field reflected in this still-active fault regime. It has continued to develop in this style, despite the regional transpressional stress field prevailing in the western sector of the northwards-convex North Anatolian Fault Zone. New radiometric dates obtained from travertine deposits developed along the NAFZ master strand on the southern border of the Bolu Basin show that the basin is older than 3 × 105 years. Dip-slip normal faults observed in the poorly consolidated Quaternary fluvial sediments forming the basin floor display both ENE-WSW and N-S trends, in accordance with the transtensional kinematics of a pull-apart. The 4.5 metre co-seismic right-lateral displacement in the middle part of the Gölyaka-Kaynaşli{dotless} segment of the NAFZ that occurred during the 12 November 1999 earthquake appears to have loaded stress on to the eastern part of this segment, possibly causing it to propagate eastwards, into the middle of the Bolu pullapart basin and creating an east-west-trending high strain zone north of Bolu city, suggesting the route of the possible continuation of the segment. ©TÜBİTAK.


Yilmaz N.,Disaster and Emergency Management Presidency | Yucemen M.S.,Middle East Technical University
Geodinamica Acta | Year: 2015

Influence of different models and assumptions with respect to seismic source modelling and magnitude distribution on seismic hazard results is examined, taking Jordan as a case study. Four alternative models, which are based on different combinations of seismic source models and magnitude-recurrence relationships, are considered. Seismic hazard curves obtained at four different sites in Jordan according to these four models are compared. In order to display the magnitude of spatial variation of peak ground acceleration (PGA) values obtained from these models, difference maps for return periods of 475 and 2475 years are constructed. Logic tree method is applied to aggregate the results calculated based on different models and assumptions. Then, best estimate seismic hazard maps for PGA and spectral acceleration at 0.2 and 1.0 s corresponding to return periods of 475 and 2475 years are plotted. © 2014 Taylor & Francis.


Avsar O.,Disaster and Emergency Management Presidency | Caner A.,Middle East Technical University | Sarici B.,RUA Engineering
Advanced Materials Research | Year: 2011

The existing Komurhan Bridge was built over the dam reservoir prior to water storage. The aging segmental post-tensioned concrete bridge with two lanes had an active sagging problem at its mid-span. As the traffic demand increased over the years, the authorities decided to add two more lanes to have a twin two-lane road for this part of highway network. Therefore, a need was developed to build a new bridge. Unlike the existing one, the suggested crossing needed to pass 300 meters wide water body with a depth of 45 meters to avoid piers at water body. Couple of alternatives was considered to cross the deep water at conceptual design phase. The focus of this study is given to the conceptual design of a cable-stayed bridge with two towers crossing the water at the narrowest location. This option results in a curved back span at one side of the water. A three-dimensional computer model was developed to assess challenges in design. Special care is given to the design details of the cables and the superstructure. Even if one of the back spans is curved, the proposed conceptual cable-stay bridge design is satisfactory under service and earthquake loads. © (2011) Trans Tech Publications, Switzerland.


Yilmaz N.,Disaster and Emergency Management Presidency | Semih Yucemen M.,Middle East Technical University
Soil Dynamics and Earthquake Engineering | Year: 2011

Spatial sensitivity of seismic hazard results to different models with respect to background seismic activity and earthquake occurrence in time is investigated. For the contribution of background seismic activity to seismic hazard, background area source with uniform seismicity and spatially smoothed seismicity models are taken into consideration. For the contribution of faults, through characteristic earthquakes, both the memoryless Poisson and the time dependent renewal models are utilized. A case study, involving the assessment of seismic hazard for the Bursa province in Turkey, is conducted in order to examine quantitatively the influence of these models on seismic hazard results. The spatial variation of the difference in Peak Ground Acceleration (PGA) values obtained from these different models is presented in the form of difference maps for return periods of 475 and 2475 years. Best estimate seismic hazard maps for PGA and Spectral Accelerations (SA) at 0.2 and 1.0. s are obtained by using the logic tree method. © 2011 Elsevier Ltd.


Yilmaz N.,Disaster and Emergency Management Presidency | Yucemen M.S.,Middle East Technical University
Applications of Statistics and Probability in Civil Engineering -Proceedings of the 11th International Conference on Applications of Statistics and Probability in Civil Engineering | Year: 2011

In the probabilistic seismic hazard analysis, the past earthquake records that can not be associated with any one of the specific faults are treated as background seismic activity. Contribution of background seismic activity to seismic hazard is generally calculated by using two different models, namely: background area source with uniform seismicity and spatially smoothed seismicity model. In this study, two case studies are carried out for a large (a country) and a small region (a province) in order to investigate the sensitivity of seismic hazard results to the models used to describe background seismic activity. For this purpose, spatial variation of differences between the seismic hazard values obtained from these two models are mapped and examined for return periods of 475 and 2475 years. © 2011 Taylor & Francis Group, London.


Yilmaz N.,Disaster and Emergency Management Presidency | Avsar O.,Anadolu University
Natural Hazards | Year: 2013

Reconnaissance observations are presented on the building damage caused by the May 19, 2011, Kütahya-Simav earthquake in Western Turkey as well as an overview of strong ground motion data recorded during the earthquake is given. According to Disaster and Emergency Management Presidency of Turkey, the magnitude of the earthquake is 5.7 in local magnitude scale. Although the earthquake can be regarded as a moderate event when considering its magnitude and strong motion recordings, it caused excessive structural damage to buildings in Simav district and several villages in the near vicinity. During the field investigation, different types of structural damage were observed mainly in the reinforced concrete frame buildings with infill walls and masonry buildings with various types of construction materials. Observed damage resulted from several deficiencies in structural and non-structural components of the buildings. Poor construction materials and workmanship, non-conforming earthquake-resistant design and construction techniques and non-ductile detailing are the main reasons for such an extensive damage, as observed in many past earthquakes in Turkey. © 2013 Springer Science+Business Media Dordrecht.


Kal M.B.,Disaster and Emergency Management Presidency | Miyake H.,University of Tokyo
Bulletin of the International Institute of Seismology and Earthquake Engineering | Year: 2012

On 8 March 2010, an earthquake of MW=6A occurred in Elazig and Kovancilar in Turkey. This event is known as the 2010 Elazig Kovancilar earthquake. It caused massive destruction in the rural areas affected and claimed lives. We performed the empirical Green's function method to simulate the strong ground motion of this event and the largest aftershock recorded with magnitude Mw=5.5, utilizing strong ground motion data from strong motion and broadband velocity stations. We then converted these records into a uniform sampling frequency to carry out the simulation. Amplitude spectral analysis was used to find an estimation of parameters used in the empirical Green's function method. The focal mechanism determined by Tan et al. (2011) was used for the simulation of the mainshock and the largest aftershock. The best source model was estimated by fitting the synthetic acceleration, velocity and displacement to the observed seismograms. The obtained size of the estimated strong ground motion generation area was calculated as 2.80 km in length by 2.00 km in width for both the mainshock and the aftershock. The rupture starting point was found to be at northeast and southwest of the estimated strong ground motion area for the mainshock and the largest aftershock, respectively. We determined the scaling parameter for the mainshock as 2 and the stress drop correction factor is 3.5. The determined scaling parameter for the largest aftershock is 2 and the stress drop correction factor is 2.5. The above analyses suggest that the stress drop correction factor of the strong motion generation area for the mainshock is 1.4 times higher than that for the largest aftershock. The 2010 Elazig Kovancilar earthquake is characterized by shallow depth rupture with high stress drop. This fact is considered to be one of the source effects to generate severe ground motion for the damaging earthquake.

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